40x Microscope objective

ABSTRACT

A five-component 40x microscope objective having a plano-convex positive doublet as the third element providing sufficient color correction to permit classification as a semi-apochromatic objective is disclosed.

BACKGROUND OF THE INVENTION

This invention relates to improvements in microscope objectives, and inparticular to a semi-apochromatic microscope objective with a numericalaperture of substantially 0.80, and a magnification of substantially 40xwhen used with a telescope lens. It is the object of this invention toprovide such a microscope objective in which the usual chromatic imageaberrations are exceptionally well-corrected as well as sphericalaberration, coma, and astigmatism, while having a substantially flatimage over a 20 millimeter field when used with telescope as describedin U.S. Pat. No. 3,355,234 and a typical 10x eyepiece.

Prior Art

U.S. Pat. No. 3,552,831 issued to Shoemaker, Jan. 5, 1971. This patentdiscloses a three member achromatic 40x objective having three members.The first member is a meniscus singlet and the second and third membersare each bi-convex doublets.

U.S. Pat. No. 3,623,792 issued Nov. 30, 1971 to Uetake. The patentdiscloses a 40x objective having three doublets. The first doublet ismeniscus shaped while the second and third doublets are bi-convex.

U.S. Pat. No. 3,879,111 issued Apr. 22, 1975 to Guto. This patentdiscloses a five member 40x objective having a meniscus first element, ameniscus second element, a bi-convex doublet as the third element, ameniscus doublet as the fourth element and a meniscus doublet as thefifth element. The first, second and fourth elements have the concavesurface of the meniscus lens on the object side of the element with thefifth element having the concave surface on the side opposite the objectside of the element.

THE DRAWING AND THE INVENTION

The drawing is an optical diagram of the preferred form of the presentinvention wherein the numeral X designates the objective in general, andthe numerals I, II, III, IV, and V designate the five optically alignedlenses of said objective. The foremost lens I is a concavo-convexpositive singlet. Rearward of lens I is lens II, a concavo-convexpositive doublet, followed respectively by lens III, a plano-convexpositive doublet, and lens IV, a bi-convex positive triplet. Therearmost lens V is a concavo-convex negative doublet.

THE DESCRIPTION

With respect to the lens parameters, the axial thicknesses of successivelens elements are designated T₁ to T₁₀ and the successive axial spacesfrom the object plane (designated O) are S₁ to S₅. The successive lensradii are designated R₁ to R₁₅ where the minus sign (-) applies tosurfaces whose center of curvature lies on the object side of theirvertices. The refractive indices and Abbe numbers of the glasses in thesuccessive lenses are designated ND(1) to ND(10), and V(1) to V(10)respectively.

                                      TABLE I                                     __________________________________________________________________________                             Refractive                                                                             Abbe                                           Radius  Thickness                                                                            Space  Index    Number                                      Lens                                                                             (R)     (T)    (S)    (ND)     (ν)                                      __________________________________________________________________________                      S.sub.1 = 0.066 f                                              R.sub.1 = -0.473 f                                                         I          T.sub.1 = 0.504 f                                                                           1.78< ND.sub.1 <1.79                                                                   49.7<ν.sub.1 <50.7                          R.sub.2 = -0.552 f                                                                           S.sub.2 = 0.040 f                                              R.sub.3 = -2.755 f                                                                    T.sub.2 = 0.263 f                                                                           1.52<ND.sub.2 <1.53                                                                    51<ν.sub.2 <52                           II R.sub.4 = 2.835 f                                                                     T.sub.3 = 0.723 f                                                                           1.48<ND.sub.3 <1.49                                                                    84<ν.sub.3 <85                              R.sub.5 = -1.052 f                                                                           S.sub.3 = 0.125 f                                              R.sub.6 = ∞                                                                     T.sub.4 = 0.285 f                                                                           1.51<ND.sub.4 <1.52                                                                    63.5<ν .sub.4 <64.5                      III                                                                              R.sub.7 = 1.433 f                                                                     T.sub.5 = 0.745 f                                                                           1.48< ND.sub.5 <1.49                                                                   84<ν.sub.5 <85                              R.sub.8 = -1.976 f                                                                           S.sub.4 = 1.293 f                                              R.sub.9 = 12.362 f                                                                    T.sub.6 = 0.285 f                                                                           1.51<ND.sub.6 <1.52                                                                    63.5<ν.sub.6 <64.5                          R.sub.10 = 1.228 f                                                         IV         T.sub.7 = 0.877 f                                                                           1.48<ND.sub.7 <1.49                                                                    84<ν.sub.7 <85                              R.sub.11 = -1.470 f                                                                   T.sub.8 = 0.285 f                                                                           1.69<ND.sub.8 <1.705                                                                   29.5<ν.sub.8 <30.5                          R.sub.12 = -2.389 f                                                                          S.sub.5 = 0.855 f                                              R.sub.13 = -1.838 f                                                        V          T.sub.9 = 0.438 f                                                                           1.78<ND.sub.9 <1.79                                                                    25.5<ν.sub.9 <26.5                          R.sub.14 = -1.666 f                                                                   T.sub.10 = 0.285 f                                                                          1.52<ND.sub.10 <1.53                                                                   51<ν.sub.10 <52                             R.sub.15 = -8.219 f                                                        __________________________________________________________________________

wherein the indices of refraction and Abbe numbers are absolute valuesand f is the focal length in millimeters of objective x and is about 3to 6 mm.

Numerically stated, the constructional data for one successful form ofthe invention where f is 4.563 mm is given in the following table.

                                      TABLE II                                    __________________________________________________________________________                           Refractive                                                                           Abbe                                               Radius Thickness                                                                            Space Index  Number                                          Lens                                                                             (R)    (T)    (S)   (ND)   (ν)                                          __________________________________________________________________________                     S.sub.1 = 0.299                                                 R.sub.1 = -2.157                                                           I         T.sub.1 = 2.3                                                                              ND.sub.1 = 1.786                                                                     ν.sub.1 = 50.22                                 R.sub.2 = -2.518                                                                            S.sub.2 = 0.182                                                 R.sub.3 = -12.57                                                                     T.sub.2 = 1.2                                                                              ND.sub.2 = 1.523                                                                     ν.sub.2 = 51.48                              II R.sub.4 = 12.936                                                                     T.sub.3 = 3.3                                                                              ND.sub.3 = 1.487                                                                     ν.sub.3 = 84.46                                 R.sub.5 = -4.8                                                                              S.sub.3 = 0.57                                                  R.sub.6 = ∞                                                                    T.sub.4 = 1.3                                                                              ND.sub.4 = 1.517                                                                     ν.sub.4 = 64.16                              III                                                                              R.sub.7 = 6.538                                                                      T.sub.5 = 3.4                                                                              ND.sub.5 = 1.487                                                                     ν.sub.5 = 84.46                                 R.sub.8 = -9.015                                                                            S.sub.4 = 5.9                                                   R.sub.9 = 56.403                                                                     T.sub.6 = 1.3                                                                              ND.sub.6 = 1.517                                                                     ν.sub.6 = 64.16                                 R.sub.10 = 5.603                                                           IV        T.sub.7 = 4.0                                                                              ND.sub.7 = 1.487                                                                     ν.sub.7 = 84.46                                 R.sub.11 = -6.707                                                                    T.sub.8 = 1.3                                                                              ND.sub.8 = 1.699                                                                     ν.sub.8 = 30.06                                 R.sub.12 = -10.9                                                                            S.sub.5 = 3.9                                                   R.sub.13 = -8.388                                                          V         T.sub.9 = 2.0                                                                              ND.sub.9 = 1.785                                                                     ν.sub.9 = 25.75                                 R.sub.14 = -7.599                                                                    T.sub.10 = 1.3                                                                             ND.sub.10 =  1.523                                                                   ν.sub.10 = 51.48                                R.sub.15 = -37.5                                                           __________________________________________________________________________

I claim:
 1. A semi-apochromatic microscope objective having a numericalaperture of 0.80 which comprises, aligned in sequence along an opticalaxis, a concavo-convex positive singlet I, a concavo-convex positivedoublet II, a plano-convex positive doublet III, a biconvex positivetriplet IV and a concavo-convex negative doublet V, said biconvexpositive triplet IV comprising a convex-concavo first element, abiconvex second element, and a concavo-convex third element.
 2. Themicroscope objective according to claim 1 wherein the parameters ofcomponents I, II, III, IV and V are as follows:

    __________________________________________________________________________                             Refractive                                                                             Abbe                                           Radius  Thickness                                                                            Space  Index    Number                                      Lens                                                                             (R)     (T)    (S)    (ND)     (ν)                                      __________________________________________________________________________                      S.sub.1 = 0.066 f                                              R.sub.1 = -0.473 f                                                         I          T.sub.1 = 0.504 f                                                                           1.78< ND.sub.1 <1.79                                                                   49.7<ν.sub.1 <50.7                          R.sup.2 = -0.552 f                                                                           S.sub.2 = 0.040 f                                              R.sub.3 = -2.755 f                                                                    T.sub.2 = 0.263 f                                                                           1.52<ND.sub.2 <1.53                                                                    51<ν.sub.2 <52                           II R.sub.4 = 2.835 f                                                                     T.sub.3 = 0.723 f                                                                           1.48<ND.sub.3 <1.49                                                                    84<ν.sub.3 <85                              R.sub.5 = -1.052 f                                                                           S.sub.3 = 0.125 f                                              R.sub.6 = ∞                                                                     T.sub.4 = 0.285 f                                                                           1.51<ND.sub.4 <1.52                                                                    63.5<ν.sub. 4 <64.5                      III                                                                              R.sub.7 = 1.433 f                                                                     T.sub.5 = 0.745 f                                                                           1.48< ND.sub.5 <1.49                                                                   84<ν.sub.5 <85                              R.sub.8 = -1.976 f                                                                           S.sub.4 = 1.293 f                                              R.sub.9 = 12.362 f                                                                    T.sub.6 = 0.285 f                                                                           1.51<ND.sub.6 <1.52                                                                    63.5<ν.sub.6 <64.5                          R.sub.10 = 1.228 f                                                         IV         T.sub.7 = 0.877 f                                                                           1.48<ND.sub.7 <1.49                                                                    84<ν.sub.7 <85                              R.sub.11 = -1.470 f                                                                   T.sub.8 = 0.285 f                                                                           1.69<ND.sub.8 <1.705                                                                   29.5<ν.sub.8 <30.5                          R.sub.12 = -2.389 f                                                                          S.sub.5 = 0.855 f                                              R.sub.13 = -1.838 f                                                        V          T.sub.9 = 0.438 f                                                                           1.78<ND.sub.9 <1.79                                                                    25.5<ν.sub.9 <26.5                          R.sub.14 = -1.666 f                                                                   T.sub. 10 = 0.285 f                                                                         1.52<ND.sub.10 <1.53                                                                   51<ν.sub.10 <52                             R.sub.15 = -8.219 f                                                        __________________________________________________________________________

wherein f is 3 mm to 6 mm.
 3. The microscope objective of claim 2wherein f is 4.563, ND₁ is 1.786, ND₂ and ND₁₀ are 1.523, ND₃, ND₅ andND₇ are 1.487, ND₄ and ND₆ are 1.517, ND₈ is 1.699, ND₉ is 1.785, ν₁ is50.22, ν₂ and ν₁₀ are 51.48, ν₃, ν₅ and ν₇ are 84.46, ν₄ and ν₆ are64.16, ν₈ is 30.06 and ν₉ is 25.75.